Serum amyloid A induces WISH cell apoptosis
Abstract
Aim: Serum amyloid A (SAA) is an important mammalian acute reactant. Here, we
aim to investigate the effect of SAA on apoptosis and its mechanism of action in
human amniotic WISH cells. Methods: The expression of formyl peptide receptor
(FPRL1), which is reported as a SAA receptor, was tested using RT-PCR and
ligand binding assay with radio-labeled FPRL1 ligand. The effect of SAA on
proliferating cell population was evaluated by thymidine incorporation assay.
The protein phosphorylation levels and caspase-3 activity were detected by Western
blot assay. Results: SAA inhibits thymidine incorporation in human amniotic
WISH cells. A SAA-induced decrease of proliferating cell population was accompanied
with nuclear condensation and caspase-3 activation in WISH cells, suggesting
that SAA induces WISH cell apoptosis. Since FPRL1 has been reported
as a SAA receptor, we investigated the effects of several FRPL1 agonists on a
proliferating cell population in WISH cells. Among the tested FPRL1 agonists,
only SAA induced a decrease of proliferating cell population in WISH cells. On
the downstream signaling of SAA, we found that SAA stimulated extracellular
signal-regulated kinase and p38 kinase, which were not inhibited by pertussis
toxin (PTX), ruling out the role of PTX-sensitive G-proteins. Furthermore a SAAinduced
decrease of proliferating cell population was not affected by PTX, suggesting
that SAA inhibits WISH cell apoptosis in a PTX-sensitive G-proteinindependent
manner. A SAA-induced decrease of a proliferating cell population
was completely blocked by PD98059 and SB203580, suggesting that mitogenactivated
protein kinase activities are essentially required for the process.
Conclusion: SAA is a novel inducer for WISH cell apoptosis, and the PTX-insensitive
pathway is involved in the process.
Keywords:
aim to investigate the effect of SAA on apoptosis and its mechanism of action in
human amniotic WISH cells. Methods: The expression of formyl peptide receptor
(FPRL1), which is reported as a SAA receptor, was tested using RT-PCR and
ligand binding assay with radio-labeled FPRL1 ligand. The effect of SAA on
proliferating cell population was evaluated by thymidine incorporation assay.
The protein phosphorylation levels and caspase-3 activity were detected by Western
blot assay. Results: SAA inhibits thymidine incorporation in human amniotic
WISH cells. A SAA-induced decrease of proliferating cell population was accompanied
with nuclear condensation and caspase-3 activation in WISH cells, suggesting
that SAA induces WISH cell apoptosis. Since FPRL1 has been reported
as a SAA receptor, we investigated the effects of several FRPL1 agonists on a
proliferating cell population in WISH cells. Among the tested FPRL1 agonists,
only SAA induced a decrease of proliferating cell population in WISH cells. On
the downstream signaling of SAA, we found that SAA stimulated extracellular
signal-regulated kinase and p38 kinase, which were not inhibited by pertussis
toxin (PTX), ruling out the role of PTX-sensitive G-proteins. Furthermore a SAAinduced
decrease of proliferating cell population was not affected by PTX, suggesting
that SAA inhibits WISH cell apoptosis in a PTX-sensitive G-proteinindependent
manner. A SAA-induced decrease of a proliferating cell population
was completely blocked by PD98059 and SB203580, suggesting that mitogenactivated
protein kinase activities are essentially required for the process.
Conclusion: SAA is a novel inducer for WISH cell apoptosis, and the PTX-insensitive
pathway is involved in the process.